JP5401608B2 - Dimming method and apparatus with rate control for visible light communication (VLC) - Google Patents

Description

  This application relates to wireless communications.

(Cross-reference of related applications)
This application includes US Provisional Application Serial Number 61/243862, filed September 18, 2009, US Provisional Application Serial Number 61 / 243,819 filed September 18, 2009, and Claims the benefit of US Provisional Application Serial No. 61/250811, filed Oct. 12, 2009, the contents of which are hereby incorporated by reference.

  Visible light communication (VLC) uses visible light (eg, light in the wavelength range of approximately 400 to 700 nanometers (nm) that can be seen by the human eye) to provide data (eg, audio data, numerical data). And image data) wirelessly. In order to transmit data using VLC, a visible light source such as a fluorescent bulb or light emitting diode (LED) can be turned on and off or intensity modulated at very high speeds. A receiving device (eg, camera, cell phone imaging device or ambient light sensor) receives the intensity modulated light and converts the light into data that the receiving device can process for user use and / or entertainment. Convert.

  One of the main reasons VLC is attracting attention is the ubiquitous nature of visible light sources that can be used to transmit data to receiving devices. Examples include lamps and home appliances that may include LED-backlit displays, and other LEDs such as indicator lights and traffic lights, all including one or more visible light sources. Thus, a visible light source may transmit data wirelessly to users located in most places.

  Since VLC does not need to use radio frequency bands, it can provide benefits such as unrestricting radio frequency band restrictions that are limited for use elsewhere. Furthermore, since the light source is already implemented for other purposes (eg, providing light to display television programs, movies and data), the light source can be easily facilitated by simply coupling them to a control device. It can be converted to a transmitter. However, one disadvantage of VLC is that VLC can interfere with dimming.

  VLC can be used in a variety of applications and includes, but is not limited to, the categories described in Table 1 below.

  In visible light communication (VLC), a method and apparatus for dimming a light emitter for lighting and data transmission.

  A more detailed understanding can be obtained by combining the following description, given by way of example, with the accompanying drawings.

1 is a system diagram of an example communication system in which one or more disclosed embodiments may be implemented. FIG. 1B is a system diagram of an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A. FIG. 1 is a diagram showing an IEEE 802.15.7 network topology including a communication interface. FIG. FIG. 2 is a diagram illustrating a stack of an IEEE 802.15 topology. FIG. 6 is a block diagram of a VLC physical data flow using one light emitter. 1 is a diagram illustrating an architecture of a multi-luminary. FIG. FIG. 3 is a diagram illustrating a Walsh code tree for use in VLC. It is a figure which shows the example of a data duty cycle. It is a figure which shows the example of the average brightness of a modulation | alteration. It is a figure which shows the relationship between a data duty cycle and a desired light control level or a brightness level. FIG. 2 is a diagram illustrating an embodiment of a VLC in a MAC architecture. FIG. 3 shows a proposed MAC PDU (Protocol Data Unit). It is a figure which shows MAC multiplexing and multiple access. It is a flowchart of a discovery procedure. It is a figure which shows the example of VLC dimming controlled by MAC. FIG. 4 is a block diagram illustrating a VLC including adaptation layer support.

  FIG. 1A is a diagram of an example communications system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may allow multiple wireless users to access such content through sharing of system resources including radio bands. For example, the communication system 100 may include 1 such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), and single carrier FDMA (SC-FDMA). Alternatively, multiple channel access methods can be used.

  As shown in FIG. 1A, a communication system 100 includes a wireless transmit / receive unit (WTRU) 102a, 102b, 102c, 102d, an access network (AN) or radio access network (RAN) 104, a core network 106, and a public telephone exchange. It will be appreciated that the disclosed embodiments may include any number of WTRUs, base stations, networks, and / or network elements, although the network (PSTN) 108, the Internet 110, and other networks 112 may be included. Assumed. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and / or receive wireless signals, user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, mobile phones , Personal digital assistants (PDAs), smart phones, laptop computers, netbooks, personal computers, wireless sensors, media transfer protocol (MTC) devices, consumer electronics, and the like.

  The communication system 100 may also include a base station 114a and a base station 114b. Each of the base stations 114a and 114b has a WTRU 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106, the Internet 110, and / or other networks 112. It can be any type of device configured to wirelessly interface with at least one of them. By way of example, base stations 114a, 114b can be a base transceiver base station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. . Although base stations 114a, 114b are each depicted as a single element, it will be appreciated that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

  Base station 114a is part of RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), network controller or radio network controller (RNC), relay node, etc. Can be. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals within a particular geographic region that may be referred to as a cell (not shown). The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, ie, one transceiver per sector of the cell. In another embodiment, the base station 114a may employ multiple transceivers per sector of the cell because it may use multiple input multiple output (MIMO) technology.

  Base stations 114a, 114b communicate with WTRU 102a via air interface 116, which may be any suitable wireless communication link (eg, radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). , 102b, 102c, 102d. The air interface 116 may be established using any suitable access technology or radio access technology (RAT).

  More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA. For example, base station 114a and WTRUs 102a, 102b, 102c in RAN 104 may establish technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish air interface 116 using Wideband CDMA (WCDMA). Can be implemented. WCDMA may include communication protocols such as high-speed packet access (HSPA) and / or enhanced HSPA (HSPA +). HSPA may include high speed downlink packet access (HSDPA) and / or high speed uplink packet access (HSUPA).

  In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may establish extended UMTS terrestrial radio access that may establish an air interface 116 using Long Term Evolution (LTE) and / or LTE Advanced (LTE-A). Techniques such as (E-UTRA) may be implemented.

  In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may be IEEE 802.16 (ie, global interoperability for microwave access (WiMAX)), CDMA2000, CDMA20001X, CDMA2000 EV-DO, interim standard 2000. (IS-2000), provisional standard 95 (IS-95), provisional standard 856 (IS-856), global system for mobile communications (GSM (registered trademark)), extended data rate (EDGE) for GSM evolution, Technologies such as GSM EDGE (GERAN) may be implemented.

  The base station 114b of FIG. 1A can be, for example, a wireless router, home node B, home eNode B, or access point, and facilitates wireless connectivity in local areas such as offices, homes, vehicles, campuses, etc. Any suitable access technology or RAT may be utilized. In one embodiment, base station 114b and WTRUs 102c, 102d may implement a technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d may utilize cell-based RAT (eg, WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a pico cell or femto cell. . As shown in FIG. 1A, the base station 114b may connect directly to the Internet 110. As described above, the base station 114 b may not access the Internet 110 via the core network 106.

  The RAN 104 may be any type of network configured to provide voice, data, application, and / or VoIP (Voice over Internet Protocol) services to one or more of the WTRUs 102a, 102b, 102c, 102d. , Communication with the core network 106 can be performed. For example, the core network 106 provides call control, billing services, mobile location services, prepaid phone calls, Internet connectivity, video distribution, etc. and / or a high level such as user authentication. Security functions can be performed. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 and / or the core network 106 may communicate directly or indirectly with other RANs that use the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to a RAN 104 that may use E-UTRA radio technology, the core network 106 may also communicate with another RAN (not shown) that uses GSM radio technology. .

  The core network 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. PSTN 108 may include circuit-switched telephone networks that provide conventional analog telephone line services (POTS). The Internet 110 is a collection of interconnected computer networks and devices that use common communication protocols in the TCP / IP Internet protocol suite, such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP). It may include a global system. Network 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another core network connected to one or more RANs that may use the same RAT as the RAN 104 or a different RAT.

  Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capability. That is, the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may use cell-based radio technology and a base station 114b that may use IEEE 802 radio technology.

  FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B, the WTRU 102 includes a processor 118, transceiver 120, transmit / receive element 122, speaker / microphone 124, keypad 126, display / touchpad 128, non-removable memory 106, removable memory 132, power supply 134, global positioning. A system (GPS) chipset 136 and other peripherals 138 may be included. Of course, the WTRU 102 may optionally include sub-combinations of the following elements while remaining consistent with the embodiment.

  The processor 118 is a general purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC). ), Field programmable gate array (FPGA) circuits, other types of integrated circuits (ICs), state machines, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120 and the transceiver 120 may be coupled to the transmit / receive element 122. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated within an electronic package or chip.

  The transmit / receive element 122 may be configured to transmit or receive signals to a base station (eg, base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In another embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and receive both RF and optical signals. Of course, the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

  Further, although the transmit / receive element 122 is depicted as a single element in FIG. 1B, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (eg, multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

  The transceiver 120 may be configured to modulate the signal transmitted by the transmit / receive element 122 and demodulate the signal received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capability. Thus, transceiver 120 may include multiple transceivers to allow WTRU 102 to communicate via multiple RATs, such as, for example, UTRA and IEEE 802.11.

  The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (eg, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). User input data may be received. The processor 118 may output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Further, processor 118 may access information from and store data in any suitable type of memory, such as non-removable memory 106 and / or removable memory 132. Non-removable memory 106 may include random access memory (RAM), read only memory (ROM), hard disk, or other types of memory storage devices. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as a server or a home computer (not shown).

  The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components within the WTRU 102. The power source 134 can be any device suitable for powering the WTRU 102. For example, the power source 134 may include one or more dry cells (eg, nickel cadmium, nickel zinc (NiZn), nickel hydrogen (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

  The processor 118 may be coupled to a GPS chipset 136 that may be configured to provide location information (eg, longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 receives location information from the base station (eg, base stations 114a, 114b) via the air interface 116 and / or 2 or 3 nearby. The own position can be determined based on the timing of the signal received from the base station. Of course, the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with the embodiment.

  The processor 118 may be further coupled to other peripherals 138 that may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripheral device 138 includes an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photo or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth (registered trademark) module. , Frequency modulation (FM) wireless units, digital music players, media players, video game player modules, Internet browsers, and the like.

FIG. 2 shows an IEEE 802.15.7 network topology that includes a communication interface 200. The core network (CN) 210 may be connected to the infrastructure node 225 via the Q interface 220 using technologies including, but not limited to, power line communication (PLC) or Ethernet. Infrastructure node uses R _X interface 230 which can be a VLC link, fixed, may be connected to a mobile or vehicle node 235. R _X interface 230 can be a light emitter interference used for spatial multiplexing (inter-luminary interference). P interface 240 may indicate peer-to-peer (P2P) communication that may not include connectivity to the network.

VLC can be used for a variety of applications and topologies, including P2P, infrastructure and simplex lines, and each topology can include specific modes. The infrastructure topology may include an infrastructure mode that provides communication features while maintaining illumination as a primary function of the LED source. Dimming can be implemented in this mode so that multiplexing can be used to maximize data throughput and support multiple end users. Furthermore, unintentional interference from the light source can be rejected by this mode. Also, infrastructure nodes in this mode can be linked using the R _X interface 230.

  In a P2P topology, the P2P mode may use spatial separation to limit interference from other VLC sources. Maximum data rate may be achieved by eliminating added signaling and physical layer redundancy in this mode. Also, P2P nodes in this mode can be linked using the P interface 240.

  In addition to P2P and infrastructure, VLC may utilize simplex line mode to make visible light links work as a wireless access technology that complements unidirectional support. This allows the visible light link to operate as a unidirectional broadcast channel. Also, retransmission can be repeated a fixed number of times without depending on external entities.

  FIG. 3 shows a stack 300 of an IEEE 802.15 topology. Both physical (PHY) layer 310 and MAC layer 320 are included. There may be a physical link control (LLC) layer 330 above the MAC layer. In simplex line mode, the medium access control (MAC) protocol may provide for reception of control information including acknowledgment (ACK) and channel quality measurements from external entities other than the MAC. Other LLC sublayers may also be included in the VLC architecture 340.

FIG. 4 is a block diagram 400 of a VLC PHY data flow including data band separation and aggregation using one light emitter. In FIG. 4, a single data flow is shown using a light emitter 405 to illustrate interference in a communication channel. Bit streams x ₁ , x ₂ , x ₃ ,. . , X _N 407 are input to the PHY band separator 410. N in this case is the size of the MAC protocol data unit (PDU). To ensure that the length of the vector is N, a “0” bit addition is used. In this case, N is a multiple of M, and M is the total number of data bands or color bands.

The input of the bit stream 407 to the band separator block 410 is x ₁ , x ₂ , x ₃ ,. . , X _N. Band separator 410 aggregates bitstreams across multiple data bands 415. The output of the band separator 410 is the M data band, b _m 415. Each band of data includes data bits that are mapped through a band separator. The mathematical expression that maps the data bits through the band separator can be determined by the following equation: These equations show how the input bit x is multiplexed into bit b within each band.

In this case, k is the number of channels, X is the total number of channels, m is a data band, and b _{m, k} is data.

  In order to provide maximum capacity when multiple optical bands are used in an infrastructure system, the PHY separates and aggregates data through a band separator 410. Each data symbol transmitted in parallel over the air interface is converted to a serial data stream, starting with the symbol in the lowest wavelength band and moving to the symbol in the highest wavelength band. Support for multiple wavelengths or bands is provided in infrastructure topologies. Such a band is associated with a color in the visible light spectrum and different wavelengths, with different wavelengths corresponding to different colors in the visible light spectrum. When the bands are multiplexed together, the overriding color is white light.

In channelization block 420, for each band m, data b _{m, k} is spread by a channelization code C (k, SF) specific to the light emitter. In this case, (SF) is the spreading factor of the code and k is the number of channels.

In other words, (SF) is the number of light emitters in use, and k is the index of a specific light emitter.

In the scramble or line code block 425, the scramble code S _m or line code can then be applied to the data in each band. In a direct current (DC) offset or unipolar conversion block 430, conversion of each band of data to unipolar data can occur thereafter. Conversion to DC offset or unipolar signaling may be required to be consistent with LED light source on / off keying (OOK).

  Dimming is implemented to transmit data while maintaining the brightness of the light emitter. In the dimming block 435, dimming is performed. At dimming block 435, the desired brightness level is received. Based on the desired brightness level, a data duty cycle for data transmission is determined. The filler brightness value is determined based on the received brightness level. Prior to conversion to light, a single or multi-band LED device 440 adds either “1” or “0” filler brightness values to the data, allowing for alternation of data and light to the light emitter. Become.

  Another aspect of the VLC network topology involves the separation and aggregation of PHY bands. For infrastructure VLC, three chip (band) based LEDs provide increased data rate while single chip (band) based LEDs can be used in energy efficient solutions Can do. In the case of RGB, white light is still desirable for the primary function of illumination in the sense that all bands are active. Thus, each band can be used by each light emitter to maximize data capacity. Any band that remains active for lighting purposes and does not carry data can increase system interference and reduce overall capacity.

  PHY multiplexing provides independent channels (between light emitters) in multiple light source sources so that multiple light source sources can exist simultaneously. PHY multiplexing can separate the signal from one emitter source to another. In infrastructure topologies, interference between light emitter sources can be mitigated using code division multiplexing (CDM). A variable length spreading code is defined when the spreading factor is equal to the reuse factor or the number of channels desired within the geographic region.

FIG. 5 shows a multiple light emitter architecture 500. In FIG. 5, two data flows or two light emitters 505, 508 are shown. Multiple light emitters can be present at one time. The bit stream x ₁ , x ₂ , x ₃ ,. . , X _N 507, 509 can be used as N-length input vectors and input to PHY band separators 510, 511. In order to ensure that the length of the vector is N, a "0" bit addition is used. N is a multiple of M using equation [1]. The output of the band separators 510 and 511 can be 515 and 516 M data bands for each light emitter 505 and 506, respectively.

In channelization blocks 520 and 521, a channelization code C (k, SF) is applied to the data of each band. In scrambling or line coding blocks 525 and 526, scrambling code or line code S _m is then be applied to each band of data. If there are more light emitters than diffusion codes, at least two light emitters may have the same diffusion code. In this case, a different scramble code may be used. There may be interference between the light emitters at the input port or receiver. However, the interference is mitigated by (SF). Interference can be mitigated by using CDM using variable spreading based on Walsh codes and system reuse parameters. In DC offset or unipolar conversion blocks 530, 531, conversion of each band of data to unipolar data can occur.

In the dimming blocks 535 and 536, dimming can be performed on the data of each band. In each dimming block 535, 536, the desired brightness level is received. Based on the desired brightness level, a data duty cycle for data transmission is determined. The filler brightness value is based on the received brightness level. Before the band is output to the transport channel 550, either “1” or “0” filler luminance values are added to the data by the single or multi-band LED devices 540, 541 before converting to light. The The filler luminance value or the value of filler bit b _B is determined by the following equation:

In this case, B is the average brightness of a given modulation and L is the desired illumination level.

  Data is transmitted and received using the transport channel 550 provided by the VLC physical layer. There are two different types of transport channels, broadcast channel (BCH) and shared traffic channel (STCH), depending on the subject and characteristics. BCH is a downlink channel that broadcasts the current status of the system and cell to the entire cell. STCH is a channel used for user data transmission. Since this channel is shared by many users, the data flow on this channel is managed by the scheduler and media access mechanism. The STCH is used for both uplink and downlink communications.

  FIG. 6 shows a Walsh code tree for use in VLC. The Walsh spreading code is an orthogonal code. Thus, if the light emitters are assigned with different spreading codes and the same scrambling code, and if the light emitters are transmitted synchronously, the light emitters may be separated by the receiver and may not interfere with each other. This property can be used to solve the “near-far” problem commonly encountered in wireless transmission. The perspective problem is a situation in which a receiver cannot detect a weaker signal by capturing a strong signal. By using Walsh coding for synchronization when the codes are orthogonal, the perspective problem is mitigated.

  Walsh codes have the property that the channelization code C (0, SF) is a pure DC offset even though all other codes do not have a DC offset component. After scrambling, each code becomes a random DC offset component. Although low frequency environmental noise may still interfere with the transmission, the effect is mitigated by the SF factor compared to using OOK.

  FIG. 7 shows an example data duty cycle 700. VLC may use room lighting. While the primary function of room lighting is lighting, VLC is a secondary function. Dimming is implemented to maintain communication while the light brightness changes. The brightness of the light corresponds to the proportion of the light on / off period. If the light turns off very quickly, the blink cannot be detected with the naked eye. If the light is turned on more than the number of times it is turned off, the light may appear brighter than the light that is turned off more times than it is turned on. The data flow using VLC is mapped to the time when light is on. A data duty cycle is implemented to achieve the desired brightness and maximum transmission level of data.

  In FIG. 7, the highest data duty cycle 720 over time interval T710 means that the maximum amount of data can be transmitted when the average illumination level 730 is half the maximum illumination level. For example, at 50% illumination level, the data duty cycle operates at 100%. The lowest data duty cycle means that the smallest amount of data is transmitted when the lightness is highest or lowest. For example, when the average illumination level is 100%, it means that the light is on and no data is transmitted, and when the average illumination level is 0%, the light is off. This means that no data is transmitted.

The LED filler brightness value is 1 when the minimum amount of data is transmitted and the brightness is its highest. An LED filler luminance value of 1 corresponds to an LED that is turned on and may indicate that the light is turned on. When the minimum amount of data is transmitted and the lightness is at its lowest, the LED filler brightness value is zero. An LED filler luminance value of 0 corresponds to an LED that is turned off and may indicate that the light is turned off. Over the time interval T, when no data is transmitted, the average illumination level L is a function of the data transmission duty cycle Y _B and the LED filler level.

  The desired brightness of the light source can be controlled by changing or modulating the duty cycle length of the active data transmission. Dimming is used as a link power control for communication. Data can be transmitted when the average illumination level is less than 100% and greater than 0%. When data is transmitted, the light is dimmed as a percentage.

  Dimming increases the data duty cycle when the average illumination level exceeds 50%, and dimming further forces the data duty cycle to decrease when the average illumination level is less than 50%. When the average illumination level is 50%, the data transmission is at the highest rate. In the absolute maximum brightness level and in the dark state, data transmission is not possible.

  When multiple light emitters are dimmed separately, the light emitters may have different data duty cycles. To minimize interference, the phasing of the duty cycle of multiple light emitters can be staggered. The phase of the duty cycle may be controlled by dimming blocks 535, 536 by switching point alignment or phase signal timing, ie by input from the MAC.

  Optimal performance in terms of interference is achieved when data transmission in the duty cycle of multiple light emitters has minimal overlap. This is accomplished by either guessing or removing filler bits. When the filler bit value is zero, there may be no data interference.

  FIG. 8 shows an example 800 of the relationship between the average brightness B of the LED and the modulation of the transmission by different methods. For example, data transmission can be determined by OOK or by Manchester modulation. The average brightness during the data transmission is 50% of the peak brightness. In another example, data transmission can be determined by 4-pulse position modulation (4-PPM). The average brightness during the data transmission is 25% of the peak brightness.

FIG. 9 shows the relationship between the data duty cycle Y _B and the desired dimming or brightness level. The provisional illumination level 910, which may not meet the absolute maximum LED brightness, allows for a minimum level of data transmission. L is the average illumination level desired by the user and B is the average brightness of a given modulation.

  FIG. 10 shows an embodiment 1000 where VLC is shown in the MAC architecture. The MAC subsystem interfaces with higher layers via control and data signaling. The MAC subsystem provides control packet and traffic packet classification and distribution for interfacing with higher layers, WTRU state management determined by the presence of transmitted data, packet scheduling, and downlink broadcasting for information distribution. Perform various functions including and.

  The MAC sublayer is involved in accessing the physical channel, and (1) dimming control, (2) broadcasting common data, (3) packet scheduling, (4) time division multiplexing to multiple accesses within the light emitter ( (DM) is involved in tasks that include (5) data framing including segmentation and assembly, but is not limited to these tasks.

  In order to perform the above functions, (1) reassembly / deframing block 1010, (2) state management block 1020, (3) broadcasting / common control block 1030, (4) buffer management block 1040, (5) transmission / reception control Several functional blocks are utilized, including but not limited to block 1050, (6) packet scheduling block 1060.

In FIG. 10, the mobile device MAC is a subset of the infrastructure MAC. Dimming control 1070 is performed before packet scheduling 1060. Dimming control 1070 includes a color quality index that is used to schedule and manage data flows. The MAC controls dimming by accepting the desired average illumination level L as the MAC input and determining the duty cycle γ _B from the following equation:

  If B is the average brightness of a given modulation, both the data flow and the size of the data package are based on dimming and channel measurements 1065, including channel quality index (CQI), color quality index and power level, It is not limited to these indexes.

FIG. 11 shows a MAC protocol data unit 1100 of size N _PDU . The structure of the MAC PDU includes a preamble, a PHY header 1130, a MAC header 1140, a packet delimiter start 1120, a payload 1150, and an optional frame check sequence 1160. Preamble 1110 may be used for timing and synchronization. The size of the MAC PDU can be calculated as follows.

In this case, N _F is the size of the physical layer data frame (including filler bits), γ _B is the data duty cycle, and α is the FEC code rate.

  In order to provide data services to multiple users according to the light emitter, the MAC multiple access feature can be used within the light emitter (inside the light emitter).

  FIG. 12 shows an example of MAC multiplexing and multiple access. The MAC multiple access feature may be used within the light emitter (inside the light emitter) or infrastructure node 1210 to provide data services to multiple end user nodes 1230, 1235. MAC channelization may be performed through logical channels including broadcast channel 1220, multicast channel 1240 and unicast channel 1225. The broadcast channel can be used for system information. Unicast and multicast channels may be used for user data or group data.

  A logical channel can be associated with the type and content of data transferred over the air or wireless interface. There can be different categories of data traffic mapped to logical channels. The broadcast channel may be a downlink only channel that is used to broadcast the current status capabilities of infrastructure nodes and systems to the entire light emitter domain. A broadcast channel may be mapped to a broadcast control channel (BCH). The multicast channel can be a downlink dedicated channel used to send common user data transmissions to a subgroup of users. That channel may be mapped to a shared traffic channel (STCH). Further, the per-packet identification of the group can be performed using a multicast MAC address. The unicast channel can be a point-to-point dual channel between the infrastructure node and each end user node. That channel may be used to carry user data transmissions and map to the STCH.

  FIG. 13 is a flow diagram 1300 of the discovery procedure. The discovery procedure covers the process by discovering the illuminant with which the end user associates. The discovery and association process begins with a newly turned on end-user device that has received beacons from all nearby infrastructure light emitters. When joining the illuminator domain, the new device starts receiving the configuration channel. At regular intervals, the illuminator transmits a beacon containing capabilities on the broadcast channel 1310.

  The device receiving the beacon makes a decision based on the received capability. The device processes the capabilities received from the light emitter's infrastructure node. The capabilities include PHY capability, MAC capability, unidirectional traffic support, bidirectional traffic support, dimming support, and visibility support 1320. The end-user device makes a selection of an algorithm that determines the illuminant that the device wishes to associate based on received capabilities that may also include signal measurement and data rate requirements. The end user device initiates an association process 1330-1350 by sending a request-to-associate to the selected light emitter. Once it is confirmed that the light emitter has associated with the end user, additional information is transmitted, including resource allocation information, transmission (Tx) and reception (Rx) information, CDMA parameters and bandwidth 1360 available to the user. . The end user may be able to exchange data with the light emitter on the agreed channel 1370.

FIG. 14 is a block diagram 1400 illustrating dimming controlled by the MAC. The dimming signal is received from an upper layer such as a light extraction layer (LAL). The dimming signal is used to determine the duty cycle 1420. The MAC determines a duty cycle based switching point γ _B 1430. The data is then output to the LED device 1440.

  FIG. 15 is a block diagram 1500 illustrating a VLC with adaptation layer support. Adaptation layer support is required for the MAC to perform infrastructure uplink on different radio access technologies (RATs). Management component 1560 features RAT availability, QoS mapping, control / data multiplexing options, and configuration. The management component 1560 transmits and receives information from the PHY layer 1565.

  The architecture can be used for both uplink and downlink layers: application layer 1510, middleware layer 1520, network protocol layer 1530, adaptation data layer 1540, and first technology dependent MAC layer. A first adapter 1550 coupled to the second technology and a second adapter 1555 coupled to the MAC layer depending on the second technology. Although two adapters are described in this example, the number of adapters can be limited by the number of RATs supported by the device.

  One of the challenges of VLC is that uplink and downlink availability are independent due to device constraints. In some environments, high-intensity visible light-based downlinks can be easily provided from infrastructure lighting fixtures, but the uplink is limited to the portable device's transmitted power, and spectrum other than visible light (eg, RF) May need to be provided using.

  Another feature of visible light is that the light confinement of LEDs can provide a local high bandwidth density. This can be exploited by enabling spectrum aggregation in a single direction and using multiple access techniques. Visible light collaborates in each direction, for example, using downlink visible light communication and uplink infrared communication, or by creating a hybrid topology for control and data communication through different access technologies By creating a “hot spot” functionality with multiple access technology to operate as a complementary communication link between two devices.

(Embodiment)
1. A wireless transceiver unit (WTRU) for use in dimming a light emitter for lighting and data transmission in visible light communication (VLC),
A wireless transmit / receive unit (WTRU) comprising an input port configured to receive a lightness level.

2. The WTRU of embodiment 1 further comprising a processor configured to determine a data duty cycle and filler luminance value for the data transmission based on a lightness level.

3. The WTRU as in any one of embodiments 1-2, further comprising a transmitter configured to alternately perform data transmission of the illuminant and filler luminance values.
v4. The data duty cycle is

In this case, YB represents the data duty cycle of the data transmission, L represents the illumination level, and B represents the average brightness of the light emitted from the illuminant. WTRU in either.

  5. Filler brightness value is

In this case, b _B represents the value of one or more filler bits, L represents the illumination level, and B represents the average brightness of the light emitted from the light emitter. Embodiment 2 WTRU in any of 4-4.

  6). 6. The WTRU as in any one of embodiments 2-5, wherein the amount of data transmitted is proportional to the filler luminance value.

7). A wireless transmit / receive unit (WTRU) for use in multiplexing multiple light emitter signals in visible light communication (VLC),
A wireless transceiver unit (WTRU), comprising: an input port configured to receive a plurality of light emitter signals, wherein the light emitter signal includes a plurality of data.

8). 8. The WTRU of embodiment 7, further comprising a parser configured to parse a plurality of data into one or more bands of data.

  9. 9. The WTRU as in any of embodiments 7-8, further comprising a channelization code block configured to apply a channelization code to data in each band.

  10. 10. The WTRU as in any of the embodiments 7-9, further comprising a direct current (DC) offset block configured to convert data in each band into unipolar data.

  11. Any of the embodiments 7-10, further comprising a dimmer configured to calculate a duty cycle for each band of data and to add a filler luminance value to the data for each band. WTRU in Kana.

  12 12. The WTRU as in any of embodiments 7-11, further comprising a transmitter configured to transmit data.

  13. 13. The WTRU as in any one of embodiments 7-12, wherein the illuminant signal is either within an illuminant or between illuminants.

  14 14. The WTRU as in any one of embodiments 7-13, wherein the scramble code or line code is applied to data in each band.

  15. [0060] 15. The WTRU as in any one of embodiments 7-14, wherein each band of data corresponds to a different wavelength.

  16. [0069] 18. The WTRU as in any one of embodiments 7-17, wherein each band of data has a different data duty cycle.

  17. 17. The WTRU as in any one of embodiments 7-16, wherein the amount of data transmitted through the wavelength is proportional to the amount of light transmitted through the wavelength.

18. A method of dimming a light emitter for lighting and data transmission in visible light communication (VLC) comprising:
Receiving a lightness level.

19. 19. The method of embodiment 18, further comprising: determining a data duty cycle for data transmission based on the lightness level.

20. 20. The method as in any of the embodiments 18-19, further comprising: determining a filler brightness value based on the brightness level.

21. 21. The method as in any of the embodiments 18-20, further comprising alternating illuminant data transmission and filler luminance values.

  22. The data duty cycle is

In this case, YB represents the data duty cycle of the data transmission, L represents the illumination level, and B represents the average brightness of the light emitted from the light emitter. Method in either.

  23. Filler brightness value is

In this case, b _B represents the value of one or more filler bits, L represents the illumination level, and B represents the average brightness of the light emitted from the illuminant. The method in any one of thru | or 22.

  24. 24. A method as in any of the embodiments 19-23, wherein the amount of data transmitted is proportional to the filler luminance value.

25. A method of multiplexing a plurality of light emitter signals in visible light communication (VLC),
Receiving a plurality of light emitter signals, wherein the light emitter signals include a plurality of data.

26. 26. The method of embodiment 25 further comprising parsing the plurality of data into one or more bands of data.

27. 27. The method as in any of the embodiments 25-26, further comprising applying a channelization code to the data in each band.

28. 28. The method as in any of the embodiments 25-27, further comprising converting the data in each band into unipolar data.

29. 29. The method as in any one of embodiments 25-28, further comprising: calculating a duty cycle for each band of data, and adding a filler luminance value to the data for each band based on the duty cycle.

30. 30. The method as in any one of embodiments 25-29, further comprising transmitting data for each band.

  31. 31. A method as in any of the embodiments 25-30, wherein the illuminant signal is either within an illuminant or between illuminants.

  32. 32. The method as in any of the embodiments 25-31, wherein the scramble code or line code is applied to data in each band.

  33. 33. The method as in any of the embodiments 25-32, wherein each band of data corresponds to a different wavelength.

  34. 34. The method as in any of the embodiments 25-33, wherein the data in each band has a different data duty cycle.

  35. 35. The method as in any of the embodiments 25-34, wherein the amount of data transmitted via the wavelength is proportional to the amount of light transmitted via the wavelength.

  Although features and elements are described above in particular combinations, it will be appreciated by those skilled in the art that each feature or element can be used alone or in any combination with other features and elements. . Further, the methods described herein may be implemented in a computer program, software, or firmware that is incorporated into a computer readable medium for execution by a computer or processor. Examples of computer readable storage media include electronic signals (transmitted over a wired or wireless connection) and computer readable storage media. Examples of computer readable storage media include read only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and CD-ROM disks. And optical media such as digital versatile discs (DVDs), but are not limited to these storage media. A processor in conjunction with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, MTC device, terminal, base station, RNC, or any host computer.

Claims (21)

A lighting and visible light communication (VLC) apparatus used Oite for data transmission, wherein the VLC unit,
A processor configured to determine a data duty cycle and a filler brightness value for the data transmission based on a brightness level;
A transmitter configured to alternately perform the data transmission of the illuminant and the filler luminance value, wherein the filler luminance value indicates whether the illuminant is on or off, and the filler A VLC device comprising: a transmitter whose luminance value is 0 or 1. The data duty cycle is

2, wherein γ _B represents the data duty cycle of the data transmission, L represents the illumination level, and B represents the average brightness of the light emitted from the light emitter. The VLC device described. The filler luminance value is

2, wherein b _B represents the value of one or more of the filler bits, L represents the illumination level, and B represents the average brightness of the light emitted from the light emitter. The VLC device described. The VLC device according to claim 1 , wherein an average brightness level is greater than 0% and less than 100%, and the light emitter is a visible light source .   The VLC device according to claim 1, wherein the data duty cycle is greater than 0% and less than 100%.   The VLC device according to claim 1, wherein the light emitter is a light emitting diode (LED).   The VLC device according to claim 1, wherein the brightness level is changed using dimming. A visible light communication (VLC) device for multiplexing a plurality of light emitter signals, the VLC device comprising:
An input port configured to receive the plurality of light emitter signals, wherein the light emitter signal includes a plurality of data;
A parser configured to parse the plurality of data into one or more bands of data;
A channelization code block configured to apply a channelization code to the data in each band;
A direct current (DC) offset block configured to convert the data in each band to unipolar data;
A dimmer configured to calculate a duty cycle of the data of each band and to add a filler luminance value to the data of each band;
A VLC device comprising: a transmitter configured to transmit the data. The VLC device according to claim 8 , wherein the light emitter signal is within a light emitter or between light emitters. The VLC apparatus according to claim 8 , wherein the data of each band corresponds to a different wavelength. Data for each band have a different data duty cycles, and the amount of data transmitted via the wavelength, VLC device according to claim 8, characterized in that based on the amount of light transmitted through the wavelength . A method for lighting and transmitting data in visible light communication (VLC), the method comprising:
Determining a data duty cycle for the data transmission based on a brightness level;
Determining a filler brightness value based on the brightness level;
Alternately performing the data transmission of the illuminant and the filler luminance value, wherein the filler luminance value indicates whether the illuminant is on or off, and the filler luminance value is 0 Or alternating steps, wherein the steps comprise alternating steps. The data duty cycle is

13 , wherein γ _B represents the data duty cycle of the data transmission, L represents the illumination level, and B represents the average brightness of the light emitted from the light emitter. The method described. The filler luminance value is

The basis, b _B represents the value of the one or more of the filler bits, claim 12 L represent illumination level, and B, characterized in that the representative of the average brightness of the light emitted from the light emitter The method described in 1.   The method of claim 12, wherein the data duty cycle is greater than 0% and less than 100%.   The method of claim 12, wherein the light emitter is a light emitting diode (LED).   The method of claim 12, wherein the lightness level is changed using dimming. A method of multiplexing a plurality of light emitter signals in visible light communication (VLC), the method comprising:
Receiving a plurality of light emitter signals, wherein the light emitter signal includes a plurality of data;
Parsing the plurality of data into one or more bands of data;
Applying a channelization code to the data in each band;
Converting the data in each band to unipolar data;
Calculating a duty cycle of each band of data and adding a filler luminance value to the data of each band based on the duty cycle, wherein the filler luminance value is either on or off of a visible light source or it indicates, and the filler luminance value is 0 or 1, comprising the steps of adding,
And further comprising the step of transmitting data for each band. The method of claim 18 , wherein the light emitter signal is either within a light emitter or between light emitters. The method of claim 18 , wherein each band of data corresponds to a different wavelength. Data for each band have a different data duty cycles, and the amount of data transmitted through the wavelength The method of claim 18, characterized in that based on the amount of light transmitted through the wavelength.

Images